Power supply device and control method for the same

Abstract

To provide a power supply device and a control method for the power supply device that can apply a voltage suitable for each of a motor for traveling and an auxiliary machine without increasing cost or requiring additional installation space.SOLUTION: A power supply device 1 includes: a first power source 11; a second power source 12; a switching circuit 13 having a first element SW1 to a fifth switching element SW5; and a control device 18 configured to control the switching circuit 13 to switch between a parallel state in which the first power source 11 and the second power source 12 are connected in parallel to an inverter 21 and the first power source 11 or the second power source 12 is connected to an auxiliary machine 22, and a series state in which the first power source 11 and the second power source 12 are connected in series to the inverter 21 and either the first power source 11 or the second power source 12 is connected to the auxiliary machine 22.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply device and a method for controlling a power supply device. [Background technology]

[0002] In recent years, in order to realize a low-carbon society, an increasing number of vehicles are equipped with a traction motor instead of an engine as a power generation source, or vehicles equipped with a traction motor in addition to an engine. Patent Document 1 listed below discloses a vehicle power supply system that includes a main battery that supplies power to the traction motor of such a vehicle, and a sub-battery that supplies power to auxiliary equipment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6888681 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the vehicle power supply system disclosed in the above-mentioned Patent Document 1 is equipped with two different batteries, and therefore requires different controls for each battery. Specifically, it is necessary to control the traction motor using power supplied from the main battery, and to control the voltage applied to the accessories using power supplied from the sub-battery. As such, a vehicle power supply system equipped with two different batteries requires a controller for controlling the voltage applied to the accessories in addition to a controller for controlling the traction motor, which leads to increased costs and an increased installation space.

[0005] The present invention has been made in consideration of the above circumstances, and has as its object to provide a power supply device and a control method for the power supply device that can apply voltages appropriate for each of the driving motor and the auxiliary equipment without increasing costs or the installation space. [Means for solving the problem]

[0006] The power supply device and the method for controlling the power supply device according to the present invention employ the following configuration.

[0007] (1): A power supply device according to one aspect of the present invention includes a first power supply connected between a first node and a second node, and a second power supply connected between a third node and a fourth node, and supplies power to a first electrical load connected between the first node and the fourth node and a second electrical load connected between a fifth node and a sixth node, and includes a switch having a first switch connected between the first node and the fifth node, a second switch connected between the third node and the fifth node, a third switch connected between the second node and the third node, a fourth switch connected between the second node and the sixth node, and a fifth switch connected between the fourth node and the sixth node. and a control device that switches between a parallel state in which the first power supply and the second power supply are connected in parallel to the first electric load and either the first power supply or the second power supply is connected to the second electric load by controlling the third switch of the switch circuit to an open state and the first switch, the second switch, the fourth switch, and the fifth switch to a closed state, and a series state in which the first power supply and the second power supply are connected in series to the first electric load and either the first power supply or the second power supply is connected to the second electric load by controlling the third switch to a closed state, the second switch and the fourth switch to an open state, and one of the first switch and the fifth switch to a closed state and the other to an open state.

[0008] (2): In the above aspect (1), the first power source is connected to the second electrical load when the voltage of the first power source is greater than the voltage of the second power source, and the second power source is connected to the second electrical load when the voltage of the second power source is greater than the voltage of the first power source.

[0009] (3): In the aspect (2) above, a voltage detection unit is provided that detects the voltages of the first power source and the second power source, and the control device, when the voltage of the first power source is greater than the voltage of the second power source in the series connection, controls the first switch to a closed state and the fifth switch to an open state to connect the first power source to the second electric load, and when the voltage of the second power source is greater than the voltage of the first power source, controls the first switch to an open state and the fifth switch to a closed state to connect the second power source to the second electric load.

[0010] (4): In the above aspect (3), when the control device controls the first switch to a closed state and the fifth switch to an open state, the control device first opens both the first switch and the fifth switch and then closes the first switch, and when the control device controls the first switch to an open state and the fifth switch to a closed state, the control device first opens both the first switch and the fifth switch and then closes the fifth switch.

[0011] (5): In any of the above aspects (1) to (4), when switching between the parallel state and the series state, the control device controls the switch circuit so that the voltage applied to the first electrical load gradually changes.

[0012] (6): In the above aspect (5), the control device fixes the first switch of the switch circuit to a closed state, and then alternately switches the third switch and the set of the second switch, the fourth switch, and the fifth switch to an open state and a closed state in an inverted manner, thereby switching between the series state and the parallel state while the first power source remains connected to the second electrical load.

[0013] (7): In the above aspect (5), the control device fixes the fifth switch of the switch circuit to a closed state, and then alternately switches the third switch and the set of the first switch, the second switch, and the fourth switch between an open state and a closed state in an inverted manner, thereby switching between the series state and the parallel state while the second power source remains connected to the second electrical load.

[0014] (8): In the above aspect (6) or (7), when switching from the parallel state to the series state, the control device controls so that the time during which the third switch is in a closed state gradually becomes longer and the time during which the set of multiple switches is in a closed state gradually becomes shorter, and when switching from the series state to the parallel state, the control device controls so that the time during which the third switch is in a closed state gradually becomes shorter and the time during which the set of multiple switches is in a closed state gradually becomes longer.

[0015] (9) In any of the above aspects (1) to (8), a first reactor is arranged between the first power source and the first node or the second node, and a second reactor is arranged between the second power source and the third node or the fourth node.

[0016] (10): A control method for a power supply device according to one embodiment of the present invention is a control method for a power supply device comprising a first power supply connected between a first node and a second node, and a second power supply connected between a third node and a fourth node, and supplying power to a first electrical load connected between the first node and the fourth node and a second electrical load connected between a fifth node and a sixth node, wherein the power supply device includes a switch circuit having a first switch connected between the first node and the fifth node, a second switch connected between the third node and the fifth node, a third switch connected between the second node and the third node, a fourth switch connected between the second node and the sixth node, and a fifth switch connected between the fourth node and the sixth node; and a control device that controls a switch circuit, the control device comprising: a step of controlling the third switch of the switch circuit to an open state and the first switch, the second switch, the fourth switch, and the fifth switch to a closed state to establish a parallel state in which the first power source and the second power source are connected in parallel to the first electric load and the first power source or the second power source is connected to the second electric load; and a step of controlling the third switch to a closed state, the second switch and the fourth switch to an open state, and one of the first switch and the fifth switch to a closed state and the other to an open state to establish a series state in which the first power source and the second power source are connected in series to the first electric load and either the first power source or the second power source is connected to the second electric load. [Effects of the Invention]

[0017] According to aspects (1) and (10), simply by switching between the open and closed states of a plurality of switches provided in the switch circuit, the first power source and the second power source are connected in series or in parallel to the first electrical load, and the first power source or the second power source is connected to the second electrical load. This makes it possible to apply a voltage obtained by connecting the first power source and the second power source in series or a voltage obtained by connecting the first power source and the second power source in parallel to the first electrical load, without increasing costs or installation space, while avoiding application of a voltage obtained by connecting the first power source and the second power source in series to the second electrical load.

[0018] According to aspects (2) and (3), the one having the higher voltage of the first power source and the second power source is connected to the second electrical load, thereby preventing the voltage of the first power source and the voltage of the second power source from becoming unbalanced.

[0019] According to the aspect (4), by preventing the first switch and the fifth switch from being in the closed state at the same time, it is possible to prevent the voltage of the first power supply and the second power supply connected in series from being applied to the second load, and to continue operation by applying only the voltage of the first power supply or the second power supply that is suitable for the second load.

[0020] According to the aspect (5), when switching between the parallel state and the series state, the voltage applied to the first electrical load is gradually changed, so that deterioration of only one of the first power source and the second power source can be prevented.

[0021] According to aspects (6) and (7), the series state and the parallel state are switched while the first power source remains connected to the second electrical load, or while the second power source remains connected to the second electrical load, so that the series state and the parallel state can be switched while continuing to supply power to the second electrical load.

[0022] According to the aspect (8), the parallel state and the series state are switched by gradually changing the ratio between the length of time that the third switch is in the closed state and the length of time that the set of the second switch, the fourth switch, and the fifth switch, or the set of the first switch, the second switch, and the fourth switch, are in the closed state, so that the voltage applied to the first electrical load can be gradually changed with simple control.

[0023] According to the aspect (9), a first reactor is arranged between the first power supply and the first node or the second node, and a second reactor is arranged between the second power supply and the third node or the fourth node, so that a sudden change in current can be suppressed when switching between the series state and the parallel state. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a circuit diagram showing a configuration of a main part of a power supply device according to an embodiment of the present invention; [Figure 2] 1 is a diagram illustrating an example of an operating state of a power supply device according to an embodiment of the present invention. [Figure 3] FIG. 2 is a diagram showing current paths when a power supply according to an embodiment of the present invention is operating in series mode. [Figure 4] FIG. 4 is a diagram showing an example of a change in voltage when switching between a first mode and a second mode while the power supply device according to one embodiment of the present invention is operating in a series mode. [Figure 5] FIG. 2 is a diagram showing current paths when a power supply device according to an embodiment of the present invention is operating in parallel mode. [Figure 6] FIG. 4 is a diagram showing an example of a change in voltage when a power supply device according to an embodiment of the present invention is operating in parallel mode. [Figure 7] 3 is a flowchart illustrating a control method for a power supply device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a power supply device and a method for controlling a power supply device according to the present invention will be described with reference to the drawings.

[0026] <Power supply> Fig. 1 is a circuit diagram showing the configuration of a main part of a power supply device according to one embodiment of the present invention. As shown in Fig. 1, the power supply device 1 according to this embodiment includes a first power source 11, a second power source 12, a switch circuit 13, a first reactor 14, a second reactor 15, a voltage detection unit 16, a voltage detection unit 17, and a control device 18. Such power supply device 1 supplies DC power to, for example, an inverter 21 (first electric load) that controls power running and regeneration of an electric motor M that generates driving force for the vehicle, and to an auxiliary device 22 (second electric load) provided in the vehicle. Note that, for example, a three-phase brushless DC motor or the like can be used as the electric motor M.

[0027] The first power source 11 is a chargeable and dischargeable secondary battery (for example, a battery). The positive terminal of the first power source 11 is connected to a first node N1, and the negative terminal is connected to a second node N2. The second power source 12 is a chargeable and dischargeable secondary battery (for example, a battery). The positive terminal of the second power source 12 is connected to a third node N3, and the negative terminal is connected to a fourth node N4. The first power source 11 and the second power source 12 are the same power source, and the voltage V1 of the first power source 11 and the voltage V2 of the second power source 12 are equal (or almost equal). The voltage V1 of the first power source 11 and the voltage V2 of the second power source 12 are voltages (for example, 400 V) suitable for operating the auxiliary device 22.

[0028] The inverter 21 has one end connected to the first node N1 and the other end connected to the fourth node N4. The auxiliary device 22 has one end connected to the fifth node N5 and the other end connected to the sixth node N6.

[0029] The switch circuit 13 includes five switching elements (first switching element SW1 to fifth switching element SW5 (first switch to fifth switch)) connected in series, and switches the connection states of the first power source 11, the second power source 12, the inverter 21, and the auxiliary equipment 22 under the control of the control device 18. The first switching element SW1 is connected between the first node N1 and the fifth node N5, and the second switching element SW2 is connected between the third node N3 and the fifth node N5. The third switching element SW3 is connected between the second node N2 and the third node N3. The fourth switching element SW4 is connected between the second node N2 and the sixth node N6, and the fifth switching element SW5 is connected between the fourth node N4 and the sixth node N6.

[0030] Here, the first switching element SW1 to the fifth switching element SW5 can be, for example, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). Specific connections when MOSFETs are used as the first switching element SW1 to the fifth switching element SW5 are as follows: The drain of the first switching element SW1 is connected to the first node N1, and the source is connected to the fifth node N5. The drain of the second switching element SW2 is connected to the fifth node N5, and the source is connected to the third node N3. The drain of the third switching element SW3 is connected to the third node N3, and the source is connected to the second node N2. The drain of the fourth switching element SW4 is connected to the second node N2, and the source is connected to the sixth node N6. The drain of the fifth switching element SW5 is connected to the sixth node N6, and the source is connected to the fourth node N4. A diode is connected between the source and drain of each of the first switching element SW1 to the fifth switching element SW5 in the forward direction from the source to the drain.

[0031] The switching of the switch circuit 13 is controlled by, for example, a pulse width modulated (PWM) signal that is output from the control device 18 and input to the gates of the first to fifth switching elements SW1 to SW5. A specific switching control method for the switch circuit 13 will be described later.

[0032] The first reactor 14 is disposed between the first power supply 11 and the second node N2. More specifically, one end of the first reactor 14 is connected to the negative terminal of the first power supply 11, and the other end is connected to the connection point between the source of the third switching element SW3 and the drain of the fourth switching element SW4. The second reactor 15 is disposed between the second power supply 12 and the third node N3. More specifically, one end of the second reactor 15 is connected to the positive terminal of the second power supply 12, and the other end is connected to the connection point between the source of the second switching element SW2 and the drain of the third switching element SW3.

[0033] The voltage detection unit 16 detects the voltage V1 of the first power supply 11 and outputs the detection result to the control device 18. The voltage detection unit 17 detects the voltage V2 of the second power supply 12 and outputs the detection result to the control device 18.

[0034] The control device 18 includes, for example, a connection switching control unit 18a and an electric motor control unit 18b, and performs switching control of the switch circuit 13 and drive control of the inverter 21. The connection switching control unit 18a performs switching control of the switch circuit 13 to switch the connection states of the first power source 11, the second power source 12, the inverter 21, and the auxiliary equipment 22.

[0035] Here, the power supply device 1 of this embodiment has a parallel mode and a series mode as its operating modes. The parallel mode is a mode in which the first power source 11 and the second power source 12 are connected in parallel to the inverter 21, and the first power source 11 or the second power source 12 is connected to the auxiliary equipment 22 (parallel state). The series mode is a mode in which the first power source 11 and the second power source 12 are connected in series to the inverter 21, and the first power source 11 or the second power source 12 is connected to the auxiliary equipment 22 (series state). The connection switching control unit 18a controls the switch circuit 13 to alternately switch between the parallel mode and the series mode.

[0036] Figure 2 is a diagram showing an example of the operating state of a power supply device according to one embodiment of the present invention. In the example shown in Figure 2, the operating state (status) of power supply device 1 is a parallel state before time t1 and after time t4, and a series connection between times t2 and t3. The period from time t1 to t2 is a switching period for switching from the parallel state to the series state, and the period from time t3 to t4 is a switching period for switching from the series state to the parallel state.

[0037] When the operating state of the power supply device 1 is the parallel state, the output voltage Vo of the power supply device 1 (the voltage applied to the inverter 21) becomes the voltage V1 of the first power supply 11 (or the voltage V2 of the second power supply 12). In contrast, when the operating state of the power supply device 1 is the series state, the output voltage Vo of the power supply device 1 becomes the sum (V1+V2) of the voltage V1 of the first power supply 11 and the voltage V2 of the second power supply 12. During the switching period, the output voltage Vo of the power supply device 1 becomes a value between the voltage V1 of the first power supply 11 and the voltage V2 of the second power supply 12. The operating modes and operating states of the power supply device 1 will be described in detail later.

[0038] For example, during power running of the motor M, the motor control unit 18b converts DC power applied between the positive and negative terminals on the DC side of the inverter 21 into three-phase AC power and sequentially commutates current to each phase of the motor M to supply AC current to each phase. On the other hand, during regenerative operation of the motor M, for example, the motor control unit 18b converts AC generated power output from the motor M into DC power while maintaining synchronization based on the rotation angle of the motor M.

[0039] <Serial mode> Fig. 3 is a diagram showing current paths when a power supply device according to an embodiment of the present invention is operating in series mode. Voltage detection units 16 and 17, a control device 18, and an electric motor M are not shown in Fig. 3. Figs. 3(a) and (b) show current paths during power running, and Figs. 3(c) and (d) show current paths during regenerative operation.

[0040] Here, in the series mode, there are a mode in which the first power supply 11 is connected to the auxiliary equipment 22 (hereinafter referred to as the first mode) and a mode in which the second power supply 12 is connected to the auxiliary equipment 22 (hereinafter referred to as the second mode) during both powering operation and regenerative operation. Fig. 3(a) is a diagram showing the current path in the first mode during powering operation, and Fig. 3(b) is a diagram showing the current path in the second mode during powering operation. Fig. 3(c) is a diagram showing the current path in the first mode during regenerative operation, and Fig. 3(d) is a diagram showing the current path in the second mode during regenerative operation.

[0041] As shown in Figures 3(a) to (d), during both power running and regenerative operation in series mode, the connection switching control unit 18a of the control device 18 closes (ON) the third switching element SW3 and opens (OFF) the second switching element SW2 and the fourth switching element SW4 (see also Figure 2).

[0042] As a result, as shown in Figures 3(a) and 3(b), during powering operation, a current loop LP1 is formed that passes through the second power source 12, the second reactor 15, the third switching element SW3, the first reactor 14, the first power source 11, and the inverter 21 in this order. In contrast, as shown in Figures 3(c) and 3(d), during regenerative operation, a current loop LP2 is formed that passes through the inverter 21, the first power source 11, the first reactor 14, the third switching element SW3, the second reactor 15, and the second power source 12 in this order. Note that the direction of current flow in the current loop LP2 is opposite to that of the current loop LP1 shown in Figures 3(a) and 3(b). In this way, during both powering operation and regenerative operation in the series mode, the first power source 11 and the second power source 12 are connected in series to the inverter 21.

[0043] 3(a) and 3(c), in both powering operation and regenerative operation in the series mode, in the first mode, the connection switching control unit 18a of the control device 18 closes (ON) the first switching element SW1 and opens (OFF) the fifth switching element SW5 (see also FIG. 2). This forms a current loop LP11 that passes through the first power source 11, the first switching element SW1, the auxiliary device 22, the fourth switching element SW4, and the first reactor 14 in this order. In other words, the first power source 11 is connected to the auxiliary device 22.

[0044] 3(b) and 3(d), in both powering operation and regenerative operation in the series mode, in the second mode, the connection switching control unit 18a of the control device 18 opens (OFF) the first switching element SW1 and closes (ON) the fifth switching element SW5 (see also FIG. 2). This forms a current loop LP12 that passes through the second power source 12, the second reactor 15, the second switching element SW2, the auxiliary device 22, and the fifth switching element SW5 in this order. In other words, the second power source 12 is connected to the auxiliary device 22.

[0045] The connection switching control unit 18a of the control device 18 switches between the first mode shown in Figures 3(a) and 3(c) and the second mode shown in Figures 3(b) and 3(d) based on the detection results of the voltage detection units 16 and 17. The reason for this switching is to make the voltage V1 of the first power supply 11 and the voltage V2 of the second power supply 12 the same (or almost the same).

[0046] For example, the connection switching control unit 18a switches to the first mode when the voltage V1 of the first power source 11 detected by the voltage detection unit 16 is greater than the voltage V2 of the second power source 12 detected by the voltage detection unit 17, both during powering operation and regenerative operation. On the other hand, the connection switching control unit 18a switches to the second mode when the voltage V2 of the second power source 12 detected by the voltage detection unit 17 is greater than the voltage V1 of the first power source 11 detected by the voltage detection unit 16, both during powering operation and regenerative operation.

[0047] The connection switching control unit 18a may switch between the first mode and the second mode when the magnitude of the difference between the voltage V1 of the first power supply 11 detected by the voltage detection unit 16 and the voltage V2 of the second power supply 12 detected by the voltage detection unit 17 exceeds a predetermined threshold. By switching based on the magnitude of such a difference, it is possible to avoid frequent switching between the first mode and the second mode.

[0048] 4A and 4B are diagrams showing an example of voltage changes when switching between the first mode and the second mode while the power supply device according to one embodiment of the present invention is operating in the series mode. Fig. 4A shows an example of voltage changes during power running, and Fig. 4B shows an example of voltage changes during regenerative running. In the example shown in Fig. 4, switching between the first mode and the second mode is performed when the magnitude of the difference between the voltage V1 of the first power supply 11 detected by the voltage detection unit 16 and the voltage V2 of the second power supply 12 detected by the voltage detection unit 17 exceeds a predetermined threshold.

[0049] 4(a), at time t11, the magnitude of the difference between the voltage V1 of the first power source 11 detected by the voltage detection unit 16 and the voltage V2 of the second power source 12 detected by the voltage detection unit 17 exceeds a predetermined threshold, so that switching to the first mode is performed. When switching to the first mode is performed, the power of the first power source 11 is supplied to the auxiliary equipment 22, and the voltage V1 of the first power source 11 gradually decreases.

[0050] When the voltage V1 of the first power source 11 gradually decreases and the magnitude of the difference between the voltage V1 of the first power source 11 detected by the voltage detection unit 16 and the voltage V2 of the second power source 12 detected by the voltage detection unit 17 exceeds a predetermined threshold, a switch to the second mode is performed (time t12). When the switch to the second mode is performed, the power of the second power source 12 is supplied to the auxiliary device 22, and the voltage V2 of the second power source 12 gradually decreases.

[0051] The voltage V2 of the second power supply 12 gradually decreases, and when the magnitude of the difference between the voltage V1 of the first power supply 11 detected by the voltage detection unit 16 and the voltage V2 of the second power supply 12 detected by the voltage detection unit 17 exceeds a predetermined threshold, the mode is switched back to the first mode (time t13). When the mode is switched to the first mode, the power of the first power supply 11 is supplied to the auxiliary equipment 22, so that the voltage V1 of the first power supply 11 gradually decreases. In this way, during power running operation, the mode is switched between the first mode and the second mode, so that the voltage V1 of the first power supply 11 and the voltage V2 of the second power supply 12 decrease in approximately the same manner.

[0052] 4(b), at time t11, the magnitude of the difference between the voltage V1 of the first power source 11 detected by the voltage detection unit 16 and the voltage V2 of the second power source 12 detected by the voltage detection unit 17 exceeds a predetermined threshold, and therefore switching to the first mode is performed. When switching to the first mode is performed, the power of the first power source 11 is supplied to the auxiliary device 22, but since the regenerated power is stored in the first power source 11, the voltage V1 of the first power source 11 gradually increases.

[0053] When the voltage V1 of the first power source 11 gradually increases and the magnitude of the difference between the voltage V1 of the first power source 11 detected by the voltage detection unit 16 and the voltage V2 of the second power source 12 detected by the voltage detection unit 17 exceeds a predetermined threshold, a switch to the second mode is performed (time t22). When the switch to the second mode is performed, the electric power of the second power source 12 is supplied to the auxiliary device 22, but since the regenerated electric power is stored in the second power source 12, the voltage V2 of the second power source 12 gradually increases.

[0054] Voltage V2 of second power supply 12 gradually increases, and when the magnitude of the difference between voltage V1 of first power supply 11 detected by voltage detection unit 16 and voltage V2 of second power supply 12 detected by voltage detection unit 17 exceeds a predetermined threshold, switching to the first mode is performed again (time t23). When switching to the first mode is performed, power from first power supply 11 is supplied to auxiliary equipment 22, but because regenerated power is stored in first power supply 11, voltage V1 of first power supply 11 gradually increases. In this way, during regenerative operation, switching between the first mode and the second mode causes voltage V1 of first power supply 11 and voltage V2 of second power supply 12 to increase in approximately the same manner.

[0055] When switching from the second mode to the first mode, the connection switching control unit 18a first opens both the first switching element SW1 and the fifth switching element SW5 and then closes the first switching element SW1 (see FIG. 2). When switching from the first mode to the second mode, the connection switching control unit 18a first opens both the first switching element SW1 and the fifth switching element SW5 and then closes the fifth switching element SW5 (see FIG. 2). This prevents the voltage resulting from the series connection of the first power source 11 and the second power source 12 from being applied to the auxiliary device 22.

[0056] Parallel mode Fig. 5 is a diagram showing current paths when a power supply device according to an embodiment of the present invention is operating in parallel mode. As in Fig. 3, voltage detection units 16 and 17, control device 18, and electric motor M are not shown in Fig. 5. Figs. 5(a) and 5(b) are diagrams showing current paths during power running, and Figs. 5(c) and 5(d) are diagrams showing current paths during regenerative operation.

[0057] Here, in the parallel mode, similarly to the series mode, there are a first mode in which the first power supply 11 is connected to the auxiliary equipment 22 and a second mode in which the second power supply 12 is connected to the auxiliary equipment 22 during both powering operation and regenerative operation. Fig. 5(a) is a diagram showing the current path in the first mode during powering operation, and Fig. 5(b) is a diagram showing the current path in the second mode during powering operation. Fig. 5(c) is a diagram showing the current path in the first mode during regenerative operation, and Fig. 5(d) is a diagram showing the current path in the second mode during regenerative operation.

[0058] As shown in Figures 5(a) to (d), during both power running and regenerative operation in parallel mode, the connection switching control unit 18a of the control device 18 opens (OFF) the third switching element SW3 and closes (ON) the first switching element SW1, the second switching element SW2, the fourth switching element SW4, and the fifth switching element SW5 (see also Figure 2).

[0059] As a result, as shown in Figures 5(a) and (b), during power running, a current loop LP3 is formed that passes through the first power source 11, the inverter 21, the fifth switching element SW5, the fourth switching element SW4, and the first reactor 14 in that order, and a current loop LP4 that passes through the second power source 12, the second reactor 15, the second switching element SW2, the first switching element SW1, and the inverter 21 in that order.

[0060] 5(c) and 5(d), during regenerative operation, a current loop LP5 is formed that passes through the inverter 21, the first power supply 11, the first reactor 14, the fourth switching element SW4, and the fifth switching element SW5 in this order, and a current loop LP6 is formed that passes through the inverter 21, the first switching element SW1, the second switching element SW2, the second reactor 15, and the second power supply 12 in this order. Note that the current flow directions of the current loops LP5 and LP6 are opposite to those of the current loops LP3 and LP4 shown in FIGS. 5(a) and 5(b), respectively. In this way, during both powering operation and regenerative operation in the parallel mode, the first power supply 11 and the second power supply 12 are connected in parallel to the inverter 21.

[0061] 5(a) and 5(c), in both power running and regenerative operation in the parallel mode, in the first mode, a current loop LP21 is formed that passes through the first power supply 11, the first switching element SW1, the auxiliary equipment 22, the fourth switching element SW4, and the first reactor 14 in this order. In other words, the first power supply 11 is connected to the auxiliary equipment 22. The current loop LP21 is the same as the current loop LP11 shown in FIGS. 3(a) and 3(c).

[0062] 5(b) and 5(d), in both power running and regenerative operation in the parallel mode, in the second mode, a current loop LP22 is formed that passes through the second power supply 12, the second reactor 15, the second switching element SW2, the auxiliary equipment 22, and the fifth switching element SW5 in this order. In other words, the second power supply 12 is connected to the auxiliary equipment 22. The current loop LP22 is the same as the current loop LP12 shown in FIGS. 3(a) and 3(c).

[0063] Figure 6 shows an example of voltage changes when a power supply device according to an embodiment of the present invention is operating in parallel mode, where Figure 6(a) shows an example of voltage changes during power running, and Figure 6(b) shows an example of voltage changes during regenerative operation.

[0064] In the series mode, the connection switching control unit 18a of the control device 18 controls the first switching element SW1 and the fifth switching element SW5 to switch between the first mode and the second mode. In contrast, in the parallel mode, the connection switching control unit 18a of the control device 18 opens the third switching element SW3 (OFF) and keeps the first switching element SW1, the second switching element SW2, the fourth switching element SW4, and the fifth switching element SW5 closed (ON). In the parallel mode, natural commutation automatically switches between the first mode and the second mode depending on the magnitude relationship between the voltage V1 of the first power supply 11 and the voltage V2 of the second power supply 12.

[0065] During power running, the first mode and the second mode are automatically switched depending on the magnitude relationship between the voltage V1 of the first power source 11 and the voltage V2 of the second power source 12, and power is alternately supplied from the first power source 11 to the auxiliary equipment 22 and from the second power source 12 to the auxiliary equipment 22. As a result, as shown in Fig. 6(a), the voltage V1 of the first power source 11 and the voltage V2 of the second power source 12 gradually decrease, and the voltage V1 of the first power source 11 and the voltage V2 of the second power source 12 become approximately equal.

[0066] Even during regenerative operation, switching between the first mode and the second mode occurs automatically depending on the magnitude relationship between the voltage V1 of the first power source 11 and the voltage V2 of the second power source 12, and power supply from the first power source 11 to the auxiliary equipment 22 and power supply from the second power source 12 to the auxiliary equipment 22 are alternately performed. However, during regenerative operation, regenerated power is alternately stored in the first power source 11 and the second power source 12, so that the voltage V1 of the first power source 11 and the voltage V2 of the second power source 12 gradually increase and become approximately equal to each other, as shown in Fig. 6(b).

[0067] <Switching between parallel and serial modes> The connection switching control unit 18a of the control device 18 controls the switch circuit 13 to switch between the parallel mode and the series mode. When switching between the parallel mode and the series mode, the connection switching control unit 18a controls the switch circuit 13 so that the output voltage Vo of the power supply device 1 gradually changes, as shown in Fig. 2. Here, there are two methods for switching between the parallel mode and the series mode: a method in which the first power source 11 remains connected to the auxiliary equipment 22 (hereinafter referred to as a first switching mode), and a method in which the second power source 12 remains connected to the auxiliary equipment 22 (hereinafter referred to as a second switching mode).

[0068] The first switching mode is used when the voltage V1 of the first power supply 11 is greater than the voltage V2 of the second power supply 12. The second switching mode is used when the voltage V2 of the second power supply 12 is greater than the voltage V1 of the first power supply 11.

[0069] In the first switching mode, the connection switching control unit 18a fixes the first switching element SW1 of the switch circuit 13 to a closed state. Then, the connection switching control unit 18a alternately switches the third switching element SW3 and the set of the second switching element SW2, the fourth switching element SW4, and the fifth switching element SW5 between an open state and a closed state (see the switching period from time t1 to t2 in FIG. 2). That is, the connection switching control unit 18a alternately switches between the state shown in FIG. 3(a) or 3(c) and the state shown in FIG. 5(a) or 5(c).

[0070] In the second switching mode, the connection switching control unit 18a fixes the fifth switching element SW5 of the switch circuit 13 to a closed state. Then, the connection switching control unit 18a alternately switches the third switching element SW3 and the set of the first switching element SW1, the second switching element SW2, and the fourth switching element SW4 between an open state and a closed state (see the switching period from time t3 to t4 in FIG. 2). That is, the connection switching control unit 18a alternately switches between the state shown in FIG. 3(b) or FIG. 3(d) and the state shown in FIG. 5(b) or FIG. 5(d).

[0071] The first switching mode and the second switching mode can be used when switching from a parallel state to a series state or when switching from a series state to a parallel state. Specifically, when switching from a parallel state to a series state, the first switching mode can be used when the voltage V1 of the first power supply 11 is greater than the voltage V2 of the second power supply 12, and the second switching mode can be used when the voltage V2 of the second power supply 12 is greater than the voltage V1 of the first power supply 11. Also, when switching from a series state to a parallel state, the first switching mode can be used when the voltage V1 of the first power supply 11 is greater than the voltage V2 of the second power supply 12, and the second switching mode can be used when the voltage V2 of the second power supply 12 is greater than the voltage V1 of the first power supply 11.

[0072] When switching from the parallel state to the series state using the first switching mode, the connection switching control unit 18a controls the third switching element SW3 so that the time during which the third switching element SW3 is in the closed state gradually increases, and the time during which the set of the second switching element SW2, the fourth switching element SW4, and the fifth switching element SW5 is in the closed state gradually decreases (see the switching period between times t1 and t2 in FIG. 2). Specifically, the connection switching control unit 18a controls the third switching element SW3 and the set of the second switching element SW2, the fourth switching element SW4, and the fifth switching element SW5 so that the duty (parallel state period / (parallel state period+series state period)) changes from 0% to 100%. The control frequency is, for example, 10 to 300 KHz.

[0073] When switching from the parallel state to the series state using the second switching mode, the connection switching control unit 18a controls the third switching element SW3 so that the time during which the third switching element SW3 is in the closed state gradually increases and the time during which the set of the first switching element SW1, the second switching element SW2, and the fourth switching element SW4 is in the closed state gradually decreases. Specifically, the connection switching control unit 18a controls the third switching element SW3 and the set of the first switching element SW1, the second switching element SW2, and the fourth switching element SW4 so that the duty changes from 0% to 100%.

[0074] When switching from the series state to the parallel state using the second switching mode, the connection switching control unit 18a controls the third switching element SW3 so that the time during which the third switching element SW3 is in the closed state gradually shortens and the time during which the set of the first switching element SW1, the second switching element SW2, and the fourth switching element SW4 is in the closed state gradually lengthens (see the switching period from time t3 to t4 in FIG. 2). Specifically, the connection switching control unit 18a controls the third switching element SW3 and the set of the first switching element SW1, the second switching element SW2, and the fourth switching element SW4 so that the duty changes from 100% to 0%.

[0075] When switching from the series state to the parallel state using the first switching mode, the connection switching control unit 18a controls the third switching element SW3 so that the time during which the third switching element SW3 is in the closed state gradually shortens and the time during which the set of the second switching element SW2, the fourth switching element SW4, and the fifth switching element SW5 is in the closed state gradually lengthens. Specifically, the connection switching control unit 18a controls the third switching element SW3 and the set of the second switching element SW2, the fourth switching element SW4, and the fifth switching element SW5 so that the duty changes from 100% to 0%.

[0076] Fig. 7 is a flowchart showing a method for controlling a power supply device according to one embodiment of the present invention. The flowchart shown in Fig. 7 shows the processing performed when switching between a parallel state and a series state. The flowchart shown in Fig. 7 is started, for example, every time a higher-level device (not shown) issues a status instruction to the control device 18 of the power supply device 1.

[0077] When the process starts, the connection switching control unit 18a of the control device 18 determines whether the status instructed by the higher-level device is a series state (step S11). If it is determined that the status instructed by the higher-level device is a series state, the connection switching control unit 18a determines whether the current status of the power supply device 1 is a parallel state (step S12). If the connection switching control unit 18a determines that the current status of the power supply device 1 is not a parallel state, the process shown in FIG. 7 ends.

[0078] On the other hand, if the connection switching control unit 18a determines that the current status of the power supply device 1 is the parallel state, it sets the status of the power supply device 1 to the switching period and sets the duty to 0% (step S13). Next, the connection switching control unit 18a increases the duty by 1% (step S14). Next, the connection switching control unit 18a determines whether the duty is 100% (step S15).

[0079] If the connection switching control unit 18a determines that the duty is not 100%, it returns to the process of step S14 and increases the duty by 1%. Then, the connection switching control unit 18a again determines whether the duty is 100% (step S15). That is, the process of step S14 is repeated, and the duty is increased by 1% until it is determined in step S15 that the duty is 100%.

[0080] By performing such processing, for example, the control shown in the switching period between times t1 and t2 in Fig. 2 is performed. That is, the time during which the third switching element SW3 is in the closed state is gradually increased, and the time during which the set of the second switching element SW2, the fourth switching element SW4, and the fifth switching element SW5 is in the closed state is gradually decreased. When the connection switching control unit 18a determines that the duty is 100%, it transitions the status of the power supply device 1 to the serial state (step S16). When the above processing is completed, the connection switching control unit 18a ends the processing shown in Fig. 7.

[0081] On the other hand, if it is determined that the status instructed from the higher-level device is not a series state, the connection switching control unit 18a determines whether the current status of the power supply device 1 is a series state (step S17). If the connection switching control unit 18a determines that the current status of the power supply device 1 is not a series state, it ends the processing shown in FIG.

[0082] On the other hand, if the connection switching control unit 18a determines that the current status of the power supply device 1 is the series connection, it sets the status of the power supply device 1 to the switching period and sets the duty to 100% (step S18). Next, the connection switching control unit 18a reduces the duty by 1% (step S19). Next, the connection switching control unit 18a determines whether the duty is 0% (step S20).

[0083] If the connection switching control unit 18a determines that the duty is not 0%, the process returns to step S19, where the duty is reduced by 1%. Then, the connection switching control unit 18a again determines whether the duty is 0% (step S20). That is, the process of step S19 is repeated, and the duty is reduced by 1% until it is determined in step S20 that the duty is 0%.

[0084] By performing such processing, for example, the control shown in the switching period between times t3 and t4 in Fig. 2 is performed. That is, the time during which the third switching element SW3 is in the closed state is gradually shortened, and the time during which the set of the first switching element SW1, the second switching element SW2, and the fourth switching element SW4 is in the closed state is gradually lengthened. When the connection switching control unit 18a determines that the duty is 0%, it transitions the status of the power supply device 1 to the parallel state (step S21). When the above processing is completed, the connection switching control unit 18a ends the processing shown in Fig. 7.

[0085] As described above, the power supply device 1 of this embodiment includes the first power supply 11 connected between the first node N1 and the second node N2, and the second power supply 12 connected between the third node N3 and the fourth node N4. The power supply device 1 supplies power to the inverter 21 connected between the first node N1 and the fourth node N4, and the auxiliary device 22 connected between the fifth node N5 and the sixth node N6.

[0086] The power supply device 1 includes a switch circuit 13 and a control device 18. The switch circuit 13 includes a first switching element SW1 connected between a first node N1 and a fifth node N5, a second switching element SW2 connected between a third node N3 and a fifth node N5, a third switching element SW3 connected between the second node N2 and the third node N3, a fourth switching element SW4 connected between the second node N2 and a sixth node N6, and a fifth switching element SW5 connected between the fourth node N4 and the sixth node N6.

[0087] The control device 18 switches between a parallel state and a series state. The parallel state is a state in which the first power source 11 and the second power source 12 are connected in parallel to the inverter 21, and either the first power source 11 or the second power source 12 is connected to the auxiliary equipment 22. The series state is a state in which the first power source 11 and the second power source 12 are connected in series to the inverter 21, and either the first power source 11 or the second power source 12 is connected to the auxiliary equipment 22.

[0088] When the parallel state is established, the control device 18 controls the third switching element SW3 of the switch circuit to an open state and the first switching element SW1, the second switching element SW2, the fourth switching element SW4, and the fifth switching element SW5 to a closed state.When the series state is established, the control device 18 controls the third switching element SW3 to a closed state, the second switching element SW2 and the fourth switching element SW4 to an open state, and either the first switching element SW1 or the fifth switching element SW5 to a closed state.

[0089] As a result, by simply switching between the open state and the closed state of the multiple switching elements provided in the switch circuit 13, the first power source 11 and the second power source 12 are connected in series or in parallel to the inverter 21, and the first power source 11 or the second power source 12 is connected to the auxiliary equipment 22. This makes it possible to supply power appropriate for each of the inverter 21 and the auxiliary equipment 22 without increasing costs or the installation space.

[0090] Although the present invention has been described above using the embodiments, the present invention is not limited to these embodiments, and various modifications and substitutions can be made without departing from the spirit and scope of the present invention. For example, in the above-described embodiment, the first reactor 14 is disposed between the first power source 11 and the second node N2, and the second reactor 15 is disposed between the second power source 12 and the third node N3. However, the first reactor 14 may be disposed between the first power source 11 and the first node N1. Similarly, the second reactor 15 may be disposed between the second power source 12 and the fourth node N4.

[0091] Furthermore, the control device 18 can be realized by a computer such as an embedded computer. When the control device 18 is realized by a computer, the functions of each unit of the control device 18 are realized by a program for realizing those functions being executed by a CPU (Central Processing Unit) provided in the computer. In other words, the functions of each unit of the control device 18 are realized by software and hardware resources working together. The control device 18 may also be realized using hardware such as an FPGA (Field-Programmable Gate Array), an LSI (Large Scale Integration), or an ASIC (Application Specific Integrated Circuit). [Explanation of symbols]

[0092] 1...power supply device, 11...first power supply, 12...second power supply, 13...switch circuit, 14...first reactor, 15...second reactor, 16, 17...voltage detection unit, 18...control device, 21...inverter, 22...auxiliary equipment, N1...first node, N2...second node, N3...third node, N4...fourth node, N5...fifth node, N6...sixth node, SW1...first switching element, SW2...second switching element, SW3...third switching element, SW4...fourth switching element, SW5...fifth switching element

Claims

1. A power supply device comprising: a first power supply connected between a first node and a second node; and a second power supply connected between a third node and a fourth node; and configured to supply power to a first electrical load connected between the first node and the fourth node and a second electrical load connected between a fifth node and a sixth node, a switch circuit including a first switch connected between the first node and the fifth node, a second switch connected between the third node and the fifth node, a third switch connected between the second node and the third node, a fourth switch connected between the second node and the sixth node, and a fifth switch connected between the fourth node and the sixth node; a control device that switches between a parallel state in which the first power source and the second power source are connected in parallel to the first electric load and either the first power source or the second power source is connected to the second electric load by controlling the third switch of the switch circuit to an open state and the first switch, the second switch, the fourth switch, and the fifth switch to a closed state, and a series state in which the first power source and the second power source are connected in series to the first electric load and either the first power source or the second power source is connected to the second electric load by controlling the third switch to a closed state, the second switch and the fourth switch to an open state, and one of the first switch and the fifth switch to a closed state and the other to an open state; A power supply device comprising:

2. the first power source is connected to the second electrical load when a voltage of the first power source is greater than a voltage of the second power source; the second power source is connected to the second electrical load when the voltage of the second power source is greater than the voltage of the first power source; The power supply device according to claim 1.

3. a voltage detection unit that detects the voltages of the first power supply and the second power supply, When the voltage of the first power source is greater than the voltage of the second power source in the series connection, the control device controls the first switch to a closed state and the fifth switch to an open state to connect the first power source to the second electric load, and when the voltage of the second power source is greater than the voltage of the first power source, the control device controls the first switch to an open state and the fifth switch to a closed state to connect the second power source to the second electric load.

3. The power supply device according to claim 2.

4. When the control device controls the first switch to a closed state and the fifth switch to an open state, the control device first opens both the first switch and the fifth switch, and then closes the first switch; When the first switch is controlled to be in an open state and the fifth switch is controlled to be in a closed state, the first switch and the fifth switch are both first opened and then the fifth switch is closed.

4. The power supply device according to claim 3.

5. The power supply device according to claim 1 , wherein the control device controls the switch circuit so that the voltage applied to the first electrical load changes gradually when switching between the parallel state and the series state.

6. 6. The power supply device according to claim 5, wherein the control device fixes the first switch of the switch circuit to a closed state, and then alternately switches the third switch and a set of the second switch, the fourth switch, and the fifth switch to an open state and a closed state in an inverted manner, thereby switching between the series state and the parallel state while the first power supply remains connected to the second electrical load.

7. 6. The power supply device according to claim 5, wherein the control device fixes the fifth switch of the switch circuit to a closed state, and then alternately switches the third switch and the set of the first switch, the second switch, and the fourth switch between an open state and a closed state in an inverted manner, thereby switching between the series state and the parallel state while the second power supply remains connected to the second electrical load.

8. When switching from the parallel state to the series state, the control device performs control so that the time period during which the third switch is in a closed state gradually increases and the time period during which the set of multiple switches is in a closed state gradually decreases, When switching from the series state to the parallel state, control is performed so that the time period during which the third switch is in a closed state is gradually shortened and the time period during which the set of multiple switches is in a closed state is gradually lengthened.

8. The power supply device according to claim 6 or 7.

9. a first reactor disposed between the first power supply and the first node or the second node; a second reactor disposed between the second power supply and the third node or the fourth node; The power supply device of claim 1 .

10. A control method for a power supply apparatus comprising: a first power supply connected between a first node and a second node; and a second power supply connected between a third node and a fourth node; and the power supply apparatus supplies power to a first electrical load connected between the first node and the fourth node and a second electrical load connected between a fifth node and a sixth node, the control method comprising: The power supply device includes a switch circuit having a first switch connected between the first node and the fifth node, a second switch connected between the third node and the fifth node, a third switch connected between the second node and the third node, a fourth switch connected between the second node and the sixth node, and a fifth switch connected between the fourth node and the sixth node; a control device that controls the switch circuit, the control device controls the third switch of the switch circuit to an open state and the first switch, the second switch, the fourth switch, and the fifth switch to a closed state, thereby establishing a parallel state in which the first power source and the second power source are connected in parallel to the first electric load, and the first power source or the second power source is connected to the second electric load; the control device controls the third switch to a closed state, the second switch and the fourth switch to an open state, and one of the first switch and the fifth switch to a closed state and the other to an open state, thereby creating a series state in which the first power source and the second power source are connected in series to the first electric load and either the first power source or the second power source is connected to the second electric load; A control method for a power supply device having the above configuration.

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